The subject invention relates to an apparatus and method for printing on both sides of a sheet or other item to be printed. More particularly, it relates to an apparatus and method wherein a single printhead can be used to print on both sides of an item such as a mail piece.
FIG. 1 shows a front view of a typical mail piece 10 of the kind prepared by high volume mailers such as banks, utilities, or department stores. Typically such a high volume user will print postal indicia 12 on mail piece 10 as evidence that the appropriate postage has been paid.
As is well known, postage meters are devices which can be charged with a representation of a dollar (or other currency) amount upon payment of that amount to a postal service and which can then print postal indicia such as indicia 12 as evidence of postage payment until the amount paid is expended. To provide security, indicia 12 includes date 16, postage amount 14, and meter serial number 20, as well as other information.
Other information on mail piece 10 includes a destination address printed in field 22, a return address printed in field 24, and frequently advertising graphics or slogans in fields 28. Typically, in return for postage discounts, high volume mailers will also print routing or sorting information on the front of mail piece 10 to assist the postal service in automatically processing the mail.
Historically postal indicia have been printed by rotary or letter press impact printers which had a limited capability to vary information such as amount 14 and date 16. Such meters relied on the arbitrary and fanciful nature of significant parts of the fixed information printed in each indicia and the mechanical complexity of a mechanism for combining variable information with that fixed information, for security of the indicia. In recent years however, it has become apparent that there are many advantages to using digital, bit-mapped printing technology to print postal indicia, along with other information, on a mail piece. One disadvantage to this approach however, has been that such indicia can easily be counterfeited by anyone having access to a personal computer and a suitable printer, such as an ink jet printer.
To overcome this problem, it has been proposed to incorporate index numbers in postal indicia, so that each indicia would be unique, encrypt at least part of the information in the indicia, and print this encrypted information on mail pieces in machine readable form together with the indicia. Decryption and comparison of the information with the corresponding indicia would then demonstrate that the indicia had been produced by someone having access to the appropriate encryption key; i.e. an authorized postage meter user.
While it is believed that such encryption techniques will provide adequate security inspection of FIG. 1 shows that there maybe substantial difficulty finding space for the encrypted information on the face of mail piece 10. Further, large amounts of encrypted information, typically in barcode form, would give mail piece 10 a cluttered and unattractive appearance.
Accordingly, it is an object of the subject invention to provide a printing mechanism, suitable for use in a postage meter, which has a capability for printing bit-mapped indicia on both sides of a mail piece or other item to be mailed.